Magnetic Field Lines

Magnets are surrounded by magnetic fields. A magnetic field can be thought of as consisting of lines of force. The forces of magnetic attraction and repulsion move along the lines of force. The magnet below is being placed on a surface containing iron filings.

Click ON to simulate the placing of a magnet on a surface covered with iron filings.

The iron filings line up along the magnetic field lines of the magnet. Note the circular pattern of the field lines. By convention, we say that the field lines emanate from the north pole of the magnet and re-enter the magnet through the south pole. Note also that the field lines are closer together at the poles than at the center of the magnet. More iron filings are attracted to the poles because the strength of the magnetic field is greater at the poles.